v3.3.1.900
Capital Structure
 12 Months Ended
Dec. 31, 2015
Capital Structure [Abstract]  
Capital Structure
Capital Structure
Common Stock
Our authorized common stock consists of 1.4 billion shares of Calpine Corporation common stock. Common stock issued as of December 31, 2015 and 2014, was 356,755,747 shares and 502,287,022 shares, respectively, at a par value of $0.001 per share. Common stock outstanding as of December 31, 2015 and 2014, was 356,662,004 shares and 381,921,264 shares, respectively. The table below summarizes our common stock activity for the years ended December 31, 2015, 2014 and 2013.
 
Shares
Issued
 
Shares
Held in
Treasury
 
Shares
Outstanding
Balance, December 31, 2012
492,495,100

 
(35,446,130
)
 
457,048,970

Shares issued under Calpine Equity Incentive Plans
5,345,956

 
(2,323,828
)
 
3,022,128

Share repurchase program
—

 
(31,032,110
)
 
(31,032,110
)
Balance, December 31, 2013
497,841,056

 
(68,802,068
)
 
429,038,988

Shares issued under Calpine Equity Incentive Plans
4,445,966

 
(1,879,167
)
 
2,566,799

Share repurchase program
—

 
(49,684,523
)
 
(49,684,523
)
Balance, December 31, 2014
502,287,022

 
(120,365,758
)
 
381,921,264

Shares issued under Calpine Equity Incentive Plans
2,431,236

 
(1,089,328
)
 
1,341,908

Share repurchase program
—

 
(26,601,168
)
 
(26,601,168
)
Retirement of shares held in treasury
(147,962,511
)
 
147,962,511

 
—

Balance, December 31, 2015
356,755,747

 
(93,743
)
 
356,662,004


Treasury Stock
As of December 31, 2015 and 2014, we had treasury stock of 93,743 shares and 120,365,758 shares, respectively, with a cost of $1 million and $2.3 billion, respectively. During 2015, we repurchased a total of 26.6 million shares of our outstanding common stock for approximately $529 million at an average price of $19.87 per share. Our treasury stock also consists of our common stock withheld to satisfy federal, state and local income tax withholding requirements for vested employee restricted stock awards and net share employee stock options exercises under the Equity Plan. All treasury stock is held at cost.